This is a continuation-in-part of co-pending U.S. patent application Ser. No. 129,416, filed Nov. 25, 1987, now U.S. Pat. No. 4,765,505, entitled "Delayed Release Fuel Cap," which is a continuation of U.S. patent application Ser. No. 042,791, filed Apr. 27, 1987, now abandoned, which is a continuation-in-part of U.S. patent application Ser. No. 888,575, filed July 22, 1986, entitled "Pressure Release Fuel Cap," now U.S. Pat. No. 4,676,390, granted June 30, 1987.
The present invention relates to fuel caps for closing filler necks of vehicle fuel tanks. More particularly, the present invention relates to a fuel cap that enables fuel vapor to vent from the tank upon rotation of the fuel cap in the removal direction.
Conventional fuel caps for closing the filler neck of vehicle fuel tanks generally include a pressure-vacuum valve located in the cap to control the pressure within the fuel tank. Whenever the pressure within the tank reaches a predetermined superatmospheric level, the pressure valve portion of the pressure-vacuum valve automatically opens to prevent excess pressure build-up. Whenever the pressure within the tank drops to a predetermined subatmospheric level, the vacuum valve portion of the pressure-vacuum valve opens to equalize the pressure in the tank.
The pressure-vacuum valve in a conventional fuel cap must be adjusted so that the potential for some vapor pressure to remain in the fuel tank exists at all times. Generally, the pressure maintained within the fuel tank is in the range of 1-2 psi. This retention of some level of fuel vapor in the tank is desired for several reasons, and normally does not create any problems. However, under certain conditions, pressure from fuel vapor can result in fuel and fuel vapor escaping from the filler neck once the fuel cap is removed. This rapid escape, or surge, of the fuel and fuel vapor from the filler neck after cap removal can result in emission of a potentially dangerous fuel vapor concentration level in the region surrounding the filler neck, as well as the Possibility that the person removing the cap could be injured by hot fuel spray.
With larger fuel tanks now being utilized in many vehicles, and, particularly, with the use of newer, more volatile blends of fuel having higher than normal Reid vapor pressure, more than normal fuel vapor pressure may be generated in these fuel tanks, particularly in warm or hot weather or after the vehicle has been running. Therefore, it would be advantageous to provide a fuel cap that will enable fuel vapor to be vented from the fuel tank sometime during the cap-removal operation, but before the cap is actually removed from the filler neck. Ideally, when the cap is used in the manner described hereinafter, this venting will be a controlled, metered venting of the fuel vapor with the fuel vapor being directed away from the operator.
Fuel caps that rotatably engage threads, cam surfaces, or the like in the filler neck of vehicles are now widely used because of their ease of installation and removal, and because of their excellent sealing characteristics. Therefore, it would be advantageous to provide a fuel cap that will enable the fuel tank to be vented in a controlled manner upon rotation of the cap in the cap-removal direction to allow the fuel vapor to be vented before the cap is removed.
Most conventional fuel caps include a primary seal that is adapted to engage a sealing lip on the filler neck when the cap is rotated fully in the cap installation direction. These conventional fuel caps generally have an outer cover that is configured to be gripped by the operator to rotate the cap. Because unseating of the primary seal can result in a surge of fuel and fuel vapor from the filler neck in warm or hot weather, or after the vehicle has been running, it would also be advantageous to provide a fuel cap that enables fuel vapor to be vented from the tank in a controlled manner upon rotation of the outer cover before the seal between the primary seal and the filler neck is broken.
It is therefore one object of the present invention to provide a fuel cap that will enable fuel vapor to be vented from the fuel tank before the fuel cap is removed from the filler neck.
Another object of the present invention is to provide a fuel cap that will enable fuel vapor to be vented from the tank automatically during a portion of the cap-removal procedure.
Yet another object of the present invention is to provide a fuel cap that will enable fuel vapor to be vented from the tank in a controlled manner while maintaining the primary seal between the fuel cap and the filler neck.
Still another object of the present invention is to provide a fuel cap having a controlled release fuel vapor venting system that enables fuel vapor to be dissipated during cap removal so as to reduce the concentration of fuel vapor in the local region surrounding the filler neck, as well as reduce the risk of expulsion of fuel from the filler neck.
Yet another object of the present invention is to provide a fuel cap having a controlled release fuel vapor venting system that is easily adapted for use in a cam-on fuel cap, and, in particular, is sufficiently compact to fit in a small space underneath the handle shell of the cap while using a minimum of parts.
One further object of the invention is to provide a fuel cap having a handle shell configured to include a cam system for moving a plunger situated between the handle shell and a companion filler neck closure to a position actuating a valve provided in the closure to vent fuel vapor from the filler neck to the atmosphere in a controlled manner in response to sufficient rotation of the handle shell in a cap-removal direction.
According to the present invention, a fuel cap is provided for use in a fuel system filler neck having a mouth. The cap includes means for engaging the filler neck, which engaging means is formed to include a filler neck venting passageway open to the atmosphere, and means for normally closing the filler neck venting passageway. The cap further includes means for selectively actuating the closing means to open the filler neck venting passageway and means for selectively rotating the engaging means relative to the filler neck in at least a cap-removal direction. The rotating means includes means for moving the actuating means against the closing means so that the closing means is moved from a passageway-closing position to a passageway-opening position upon rotation of the rotating means in the cap-removal direction prior to rotation of the engaging means.
In preferred embodiments, the moving means includes at least one cam depending from the rotating means and the actuating means includes at least one cam follower in engagement with the at least one cam. The at least one cam is cylindrical to define an axis of rotation aligned with the axis of rotation of the cap itself. Each cylindrical cam is configured to impart rectilinear movement to the actuating means in response to rotation of the cam about its axis of rotation during rotation of the rotating means in the cap-removal direction. Using this configuration, the direction of motion of the actuating means is substantially parallel to the axis of rotation of the cam and the fuel cap.
The engaging means includes a closure member configured to close the filler neck, and an inner surface defining a first venting aperture through the closure member and providing a valve seat surrounding the venting aperture. The closing means includes a pressure-relief valve formed to include a second venting aperture, a vacuum-relief valve positioned in the second venting aperture, and means for yieldably biasing the pressure-relief valve in an axially inward direction against the valve seat normally to close the first venting aperture and also for yieldably biasing the vacuum-relief valve in an axially outward direction against the pressure-relief valve normally to close the second venting aperture.
The actuating means includes a plunger axially movable in the engaging means to a vacuum-relief valve-actuating position moving the vacuum-relief valve against the biasing means upon movement of the actuating means to an actuating position. Such movement operates to open the second venting aperture in response to rotation of the rotating means relative to the filler neck.
The actuating means further includes means for blocking rotation of the plunger during axial movement toward its vacuum-relief valve-actuating position and spring means for yieldably biasing the plunger away from its vacuum-relief valve-actuating position. Preferably, the blocking means is configured to interconnect the plunger and the engaging means and the spring means acts to maintain the at least one cam follower in engagement with the at least one cam.
The engaging means includes seal means for establishing a seal with the filler neck to block the escape of fuel and fuel vapor in the filler neck to the atmosphere and a closure lid situated intermediate the seal means and the rotating means. The rotating means is an exterior handle shell and further includes means for applying a torque to the closure lid after a predetermined amount of relative movement of the shell and the filler neck to establish a "lost-motion" connection between the engaging means and the rotating means. This lost-motion connection delays breaking the seal provided by the seal means until after said predetermined amount of relative movement of the shell and the filler neck has occurred.
One feature of the present invention is the provision on the rotating means of means for moving the actuating means to actuate the closing means and open the filler neck venting passageway. In the illustrated embodiment, a handle shell serves as rotating means and includes a cam structure depending from the underside of the shell to provide moving means connected to the actuating means. Advantageously, such an economy of structure permits construction of a compact fuel cap easily configured as, for example, either a thread-on or a cam-on filler neck closure without sacrificing desirable filler neck venting control features.
Another feature of the present invention is the configuration of the moving means in the form of at least one cam depending from the rotating means so as to engage a companion cam follower formed on the actuating means. This design is well-suited for manufacturing since it is highly economical and cost-efficient to mold or otherwise produce fuel cap components which perform the required rotating and actuating functions and also include the foregoing cams and cam followers. In particular, a cylindrical cam is easily assimilated into the operating environment of a rotatable fuel cap because of its arcuate shape and axis of rotation which is capable of converting rotational cap-removing movement into, for example, axial closing means-actuating movement in cooperation with a cam follower on the actuating means.
Yet another feature of the present invention is the configuration of the actuating means as a movable plunger for actuating a vacuum-relief valve comprising a portion of the closing means to open the filler neck venting passageway. Advantageously, this feature is easily adapted to existing fuel caps having vacuum-relief valves.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.